2.3.1 The Planetary Differences:
Venus is closer to the Sun than Mars and therefore receives a greater solar radiation flux.
Venus is a slowly rotating world; Mars is a fast daily rotator.
Venus is more massive than Mars and therefore has a higher surface gravity.
At its base the atmosphere of Venus is a high-pressure, high temperature environment.
At its base the atmosphere of Mars is a low-pressure, low temperature environment.
Venus has a high planetary Bond Albedo (AV) and is therefore visibly bright and reflective.
Mars has a low planetary Bond Albedo (AM)and is therefore visibly dull and poorly reflective.
The exit-to-space thermal radiation emission height of Venus is in the planet’s stratosphere at an elevation of 71 Km.
The exit-to-space thermal radiation emission height of Mars is in the planet’s surface boundary layer at an elevation of 1.6 Km.
2.3.2 The Atmospheric Similarities:
Both Venus and Mars contain an abundance of carbon dioxide gas in their respective atmospheres (Venus 96.5%; Mars 95.1%).
Both Venus and Mars have an equivalent tropopause elevation (Venus 63.4 Km; Mars 62.0 Km) this is despite the massive differences in the pressure and temperature profiles of the two planet’s tropospheres (Figure 3) and an requires an explanation.